I heard over the years that there's a lot of investment in UP by members of the Mormon church. With investment comes influence.
It goes back to the golden spike. There's a book about the 40 years it took to build the Salt Lake Temple and an excerpt is on
Utahrails"The temple was constructed of gray granite taken from a mountain of that enduring material in Little Cottonwood Canyon, twenty miles southeast of Salt Lake City. Many of the blocks of granite in the walls are so large that four yoke of oxen were required to haul each of them, occupying four days in transit. This process of hauling rock by ox teams, from the quarry to the Temple site, was so slow and expensive that President Young decided to have a canal made to carry the rock by boats. Accordingly, the canal was dug, at great cost, from the mouth of the Canyon across the bench land to an outlet in City Creek, near Temple block. But in 1873, before the canal was sufficiently completed to be made available for the main purpose in view, a line of railway was laid which supplanted this contemplated use of the canal. (Our Pioneer Heritage, Vol. 14, p.415)
The entrance of the Union Pacific Railway into Utah, in 1868, served temporarily to ******** the work on the Temple, as the call for laborers on the great trans-continental line was deemed imperative. Eventually, however, the activity in railroad construction operated as a great assistance in the undertaking; for, to the main line, branches succeeded; and, by 1873, a side line had reached the granite quarries. From the city station a track was constructed up South Temple Street, and into Temple Block. (James E. Talmage, The House of the Lord, p.122 - p.123)"